Phasable ganged potentiometer



E; BLANCO PHASABLE GANGED POTENTIOMETER Aug. 13, 1963 2 Sheets-Sheet 1 Filed Nov; 21, 1960 a/ s BZA/VCO,

3,100,883 PHASABLE GANGED POTENTIOMETER Elias Blanca, L'os Angeles, Calif., assignor, by ,mesne assignments, to Daystrom'lncorporated, Murray Hill, NJ., a corporation of Texas v Filed Nov. 21, 1960, Se1'. No. 70,844 3 Claims. '(Cl. 338148) The present invention relates generally to variable resistors or otentiometers, and is more particularly concerned with devices of this type which may be built in miniature or extremely small size units, and which may be utilized singly or ganged together.

The present application constitutes a continuation-in part of my copending application-f entitled Phasable Ganged Potentiometer, Serial'No. 752,912, filed August 4, l958,now Patent No. 2,968,015.

Heretofore, potentiometer units have been ganged by securing the casings together by means of clamping rings which would permit individual units to be phased by shifting of the respective casings. This necessitated a loosening of the ganged assembly and-necessitated a readjustment of the phasing of each unit and a recheck before the clamping rings were again tightened. The

conventional constructions were very inconvenient and hard to adjust. Moreover since the terminals'for each casing were in'fixed relation to the casing, shifting of the casings-1 during phasing also resulted in'a shifting of It was therefore diflicult to use a pre-' 'can be adjusted after the'casings are assembled, thus making it unnecessary tojhave positionprior to assembly.

Still another object is to provide a novel potentiometer construction, wherein the wiper contact isphasable to calculate the wiper through 360.

Still another object is to I provide improved means for securing the potentiometer units in ganged relation in such a way'as toresult-in less weight than'gang potentiometers utilizing the heretofore known arrangements. Yet another object is to provide in a'p otentiorneterpa servo mounting end 'capI of novel and improved construetion. v

Further. 'objects of the invention will be brought out in the following part of the'specification, wherein de- 1 United Stew alien/t F Patented Aug. 13, 1963 manner in which a plurality of otentiometers may be .secured together in ganged relation with their casings in end-to-end relation, tion.

FIG. 6 is a longitudinal sectional view, 2, of a modified structure; and

according to the present invensimilar to FIG.

FIG. 7 is a fragmentary view, partly in section, showvention, as generally indicated at A, are shown as being secured together in end-to-end relation to form a ganged assembly operable by an actuating shaft 10. Referring primarily to FIG. 2, the construction of a single potentiometer unit will first be described. As shown in FIG. 2, the potentiometer unit comprises a main casing 11 of molded or otherwise formed plastic or other suitable material to provide a circular cup-like member which is open at one end and at the opposite end is formed with an inturned flange 12, the inner periphery of which bounds a restricted end opening 13.

The shaft 10 is rotatably supported in end caps 14 and '15 respectively which are secured to the opposite ends of the casing 1.1. The end cap 14 may be fabricated to accommodate the potentiometer for difierent types 'of mountings. For example, the end cap 14 may be constructed for panel mounting. As shown herein, the cap provides a servo mounting, and is of generally 3O tubular bearing support 16. The shaft 10 isrotatably ring-shape configuration, being centrally formed with a supported this end 'cap by anti-friction bearing .17

having an outer race 18 which is secured and retained in the bearing support by are-taining ring 19, while the inner race 20 is secured to the shaft between a pair of snap rings 21 and 22, a spring washer 23 being" inter-' posed between one ofth ese rings and the inner race of the antifniction hearing.

The end cap 14 is secured to the casing 11 at peripherally spaced points by means of a stud 24 which has its outer end threadedly engaged with the end cap, while the other endprojects through'an opening 25 of the casing 11 into a recess 26 where it threadedly engages formed with an internal recess 28v within which antifriction'bearing 2.9; is retained, the inner race 30 of this hearing bemg'inengagememt with the adjacent end of the shaft 10, while the :outer race 31, of the bearing is retained inthe recess of the cap. The ,cap 15 is secured to the open end of the casing 11 by means of headed studs 32 which tailedf description is for the purpose of fully disclosing the invention without placing limitations thereon.

Referring to the accompanyingdrawings, which are for illustrative purposes-only:

FIG/1 is a perspective view of a ganged potentiome' ter embodying a plurality of potentiometer units con- FIG. ,4 is an enlarged ffragmentary elevational view I 0f;the casing access openingseal, as vieWedsubStantially in the direction of the arrow {of FIG. 3;

sectional view taken substam FIG. '5 is a fragmentary sectional view illustrating the H are adapted to extend through an opening in the cap 15 arranged to align with recess 26. The threaded end of the stud' SZ threadedly'engages into the adjacent end of the threaded sleeve 27. By tightening the studs 32, the cap 15 will be tightly engaged with the adjacent edge of the casing 11'. 'With the foregoing arrangement, the potentiometer components within the-casing 11 are enclosed and protected.

Th e potentiometer components include a. resistance element 34 'and an associatedwiper contact 35. The re.-

sis-tance element is seated in an annular groove or recess 36 on the inner surface of the fl'ange 12, and comprises a plurality of spiralled turns of'resistance wire 37which is wound over a supporting ring-like core member 38, suitable [insulation 39 being interposed between the wire turns and the outer surface of the core. As shown in FIG. 3, the core is split as indicated by the reference character 40, and a slight space is provided-between the'core ends, so that thecore structure may expand and contract under temperature changes. I The wiper contact 35 is carried by the shaft 10 and is as-.

sembled into a two-part supporting structure permitting movement of the wiper contact directly in response to shaft movements, and independent adjustment of the Wiper contactin order to permit phasing or a change of relative tact for a given shaft position.

More specifically, the two-part supporting structure ineludes a first part 41 fabricated from a suitable plastic or other material to provide a ciroumferentially extending radially projecting flange portion 42 and an integrally.

formed huhportion 43' which surrounds the shaft and is fixedly secured thereto as by -a set screw 44. One side of the flange '42 is formed with an annular :groove 45 for receiving one end of the second part 46 of the mounting structure for the wiper contact. The second part is :generally ring-shaped and is rotatably mounted on the hub portion of the first part. The second part has an end 47, the end which is positioned in the groove 45, fabricated to form a ring gear with teeth 48 formed on its outer periphery. The other end of the second part 46 is formed with an outwardly projecting circumferentially extending flange 49 which is adapted to bear against the adjacent face of flange 42 so as to axially locate the end 47 within the groove 45.

As shown best in FIG. 3, the wiper contact 35 is constructed with an integral ring-shaped body portion 50 which surrounds the shaft and is positioned in face engagement on one side with the end surface of the flange 49. assembly is retained in position and preloaded by means of a snap ring 51, and a spring washer 52 which bears against a metal washer 53, an insulating spacer ring.

54 being interposed between the washer 53- and the body portion 50 0f the wipercon-tact element. In order to contact with respect to the second part 46 of the support structure, the surface of the second part which is in engagement with the bo y portion 50 of the wiper contact isprovided with a socket 55 into which there extends a key- I prevent relative circumferential. movement of the wiper finger 56 formed as a part of the wiper contact, thus locking in meshed relation with the teeth 48 of the second part 4 ing may then be sealed by the simple expedientof rotating the opening 66 to a position f herein the outer end of the passage62 Will be closed.

Connection terminals 68, 69 and 70 are supported in the outer wall of casing 11, as primarily shown in FIG.

3. These terminals are connected with the components a of the potentiometer through permanently positioned eyelets 71, 72 and 73, each of the terminals being connected to an eyelet by means of a connector strip 74. As shown, the eyelets 71 and 72 are respectively connected to the ends of the resistance element, while the eyelet 73 connects with an eyelet 75, through a conductor 76. The eyelet 75 is utilized to secure a brush contact structure 77 in; fixed position on the flange 12. The brush contact has oppositely extending spring arms 78' and 78" adapted to bear against and form a sliding contact with the adjacent surface of the body portion 51] of the wiper contact structure. With the arrangement described above, it will be appreciated that the wiper contact may be rotated by rotating the shaft, 10 through a complete circle of 360, and that'also by actuating the worm and gear, phasing of the wiper contact may likewise be accomplished through a complete circle of 360*, Moreover, by utilizing a worm and gear arrangement for phasing, the wiper contact may be set at any position, and when so adjusted is locked against shifting movement by the inherent characteristics of the worm and gear drive.

One of the desirable features resulting from the potentiometer construction described above resides in the fact that the casing 11 may be constructed oi'shorter length than with conventional arrangements, and that a plurality of potentiometer units in their respective casings 11 may be secured in endrtovend axial alignment to-produce a ganged assembly in which the respective wiper contacts may be phased after assembly by simplymoving the shaft 10 to bring the actuating worms into proper position for adjustment through the passage 62 of each potentiometer casing. I

The manner in which the casings 11 are interconnected is more or less schematically illustrated in FIG. 5, wherein two casings 11a and 115 are secured in ganged assembly. It will be appreciated, however, that the gang may include additional casings as desired, and 'FIGQI shows 46. The worm 57 is ro-tatably mounted ina drilled or otherwise formed passage 58 which has an open end 59 3 in the peripheral edge of the flange 42. The worm is Ion- 'gitudinrally retained in the passage 58 by means of a keeper and groove interconnection as generally indicated by the numeral 60. The outer end of the worm member is shown as being provided with a socket 61 for receiving the end of a suitable tool by which the worm maybe rotated, as will be more fully explained subsequently. V g

I In order to permit the actuation-of the worm 57 and the adjustment of the wiper contact, after the potentiometer is fully assembled and without having to disassemble the a casing, the outer wall of the casing 11'is provided with apassage 62 which is directionally positioned in such a manner that the passage 58 may be brought into axial alignment therewith by turning the shaft 10 to proper Position. 7 r

TheTouterm-ost end of the passage 62 has an enlarged cylindrical'portion 63 which is axially positioned in eccentric relation to the axis of passage '62. A sealing plug 64 is retained in rotatable seated position in the portion 63 by a groove and keeper as generally indicated at 65. The plug 64 has an off-center opening 66 which may bebrought into and out of registration with the axis of passage 62 by inserting a small tool such as a screw driver into a receiving slot 67 in the other end of the plug. By 'rotating'the oflcenter opening into registration with the axis of the passage 62, a tool may be inserted into the socket 61 for moving the wiper contact to phase the po- 7 tentiorneter. After the adjustment is completed, the cast differs in several particulars from the structure previously i three casings ganged into a single unit.

For interconnecting additional casings, a straight stud V 79 is used instead of a headed stud such as shown at 32. The outer end of the stud 79 connects with one end of the threaded sleeve 27 of the casing which is being added. 7

To connect the end cap 15, a stud 32 is utilized in the same manner as previously, described and shown in FIG. 2.

A modified structure is illustrated in FIG. 6, which described and as shown primarily in FIG. 2. Ind-the modified arrangement, it is proposed to utilize a pinion and gear-arrangement instead of a worm and ge'ar for adjusting the phasing or relative position of the slider contact on the resistance element.

More specifically, in this modified arrnagement, it will be observed that the second'part 46 has in this case been i made of greater diameter than the first part 41, and at its periphery has been constructed as a ring gear having teeth 48' thereon. The flange 42 has in this embodiment been decreased as to diameter as indicated at 42 and peripherally engages with an annular flange 49 formedon the second part 46; This engagement is under a frictional force which is set up by means of the spring washer 52 so that under normal actuation of the shaft 10, the first part and-second part will move as a'unit, but may be relatively shiftedby means of a removable tool 80 which may be inserted through a casing opening 62', and which is arranged" at its insertable end with spur gear teeth 81 adapted to mesh with the teeth 48' of-the stem being fitted 'with a knob 83 by which the tool may be rotated. When the tool 80 is not being utilized, it may be removed, and the opening 52 closed by means of a suitable plug or sealing member (not shown).

An additional feature of the modified structure is concerned with the construction of the end cap 14 to provide an improved servo mounting of greater accuracy than that utilized on the arrangement shown in 'FIG. 2 whereby the cost of production is reduced and accurate linearity of operation is obtained.

In the construction shown in FIG, 2, the inner and outerraces of the separately. fabricated antifriction [bearing had to be concentrically fitted into the end cap, and mounting flanges at the periphery of the end cap also were, diflicult to provide in accurate concentricity to the shaft mounting. Production costs were thus materially increased. a

In the modified arrangement, the end cap 14 is made of a suitable hardened material so that it is possible to provide an end wall 84 with a central annular flange d5 integral therewith, this flange forming the outer race of the anti-friction bearing, while inner race 86 of the bearing is secured to the shaft in the usual manner. At the periphery of the end cap there is provided a circumferentially extending surface 87 which may be finished in concentric relation to the inner surface of the inner race 86 of the anti-friction hearing by comparatively simple machining methods, whereby servo mounting installations are facilitated. While the improved end cap construction has been explained in connection with its use in a potentiometer, such construction is susceptible of general application in connection with other devices.

A great advantage in being able to phase the potentiometers after the casings are in assembled relation resides in the fact that the phasing may be accomplished with my construction without disturbing the position of the terminals, thus permitting the use of a pro-assembled Wiring harness.

Various modifications may suggest themselves to those skilled in the art without departing from the spirit of my invention, and, hence, I do not wish to be restricted to the specific form shown or uses mentioned except to the extent indicated in the appended claims.

I claim:

1. A potentiometer comprising,

a casing having an opening therein,

a ringashaped resistance element in said casing,

a rotatable shaft in said casing extending axially of said resistance element,

a twoapamt support carried by said .shafit including a first part affixed to the shaft rotation therewith, and

t a second part movably supported on said first part for angularly variable positions of adjustment about the shaft axis,

said second part including a rack gear,

a slider contact carried by said second part and movable therewith over said resistance element,

and a rotatable member including a pinion drive gear having a central axis which intersects the central axis of said resistance element removably insertable through said casing opening,

said pinion drive gear having teeth adapted to mesh with the teeth of said rack gear, Wherebythe relative position of said slider contact on said resistance element may be adjusted independently of its movement through notation of said shaft.

2. In a potentiometer: a tubular casing; a ring-shaped resistance element mounted concentrically within said casing; a rotatably mounted shaft extending axially of said casing; a two-part support carried by said shaft including a first par-t afiixed to said shafit for rotation therewith, a second pant moveably supp'cnted on said first pant for angularly variable positions of adjustment about 1 the shaft axis, said second part including a gear, a slider contact carried by said second part and moveable therewith over said resistance element; means operable through said casing including a rotatable member having teeth adapted to mesh with the teeth of said gear whereby the relative position of said slider contact on said element may be adjusted independently of its movement through rotation of said shaft, end caps respectively removably secured to the ends of said casing, at least one of said end caps being of a hardened and including a peripheral circumferentially extending cylindrical suriace, and a central integral annular flange defining an outer race of an antifirioti-on bearing having an inner race ring surrounding and supponting said shaft therein, said inner race ring having its inner cylindrical surface formed concentrically with respect to said peripheral surface.

3. In a potentiometer: a tubular casing; a ring-shaped resistance element mounted concentrically within said casing; a rotatably mounted shaft extending axially of said casing; a two-part support carried by said shaft including a first part affixed to said shaft for rotation therewith, a second part moveably supported on said first pant for singularly variable'positions of adjustment about the shaft axis, said second part including a gear, a slider contact carried by said second pant and movable therewith over said resistance element; meansopera1ble through said casing including a rotatable member having teeth adapted to mesh with the [teeth of said gear whereby the relative position of said slider contact on said element may be adjusted independently of its movement through notation lOlf said shaft, end caps respectively removably secured to the ends of said casing, and at least one of said end caps having an antifriction bearing for sup porting said shaft including an inner face ring secured to said shalit and an outer race ring integrally formed with said one of said end caps.

Iorgensen et al. Mar. 13, 1956 Karg Nov. 4, 1958 

1. A POTENTIOMETER COMPRISING, A CASING HAVING AN OPENING THEREIN, A RING-SHAPED RESISTANCE ELEMENT IN SAID CASING, A ROTATABLE SHAFT IN SAID CASING EXTENDING AXIALLY OF SAID RESISTANCE ELEMENT, A TWO-PART SUPPORT CARRIED BY SAID SHAFT INCLUDING A FIRST PART AFFIXED TO THE SHAFT ROTATION THEREWITH, AND A SECOND PART MOVABLY SUPPORTED ON SAID FIRST PART FOR ANGULARLY VARIABLE POSITIONS OF ADJUSTMENT ABOUT THE SHAFT AXIS, SAID SECOND PART INCLUDING A RACK GEAR, A SLIDER CONTACT CARRIED BY SAID SECOND PART AND MOVABLE THEREWITH OVER SAID RESISTANCE ELEMENT, AND A ROTATABLE MEMBER INCLUDING A PINION DRIVE GEAR HAVING A CENTRAL AXIS WHICH INTERSECTS THE CENTRAL AXIS OF SAID RESISTANCE ELEMENT REMOVABLY INSERTABLE THROUGH SAID CASING OPENING, SAID PINION DRIVE GEAR HAVING TEETH ADAPTED TO MESH WITH THE TEETH OF SAID RACK GEAR, WHEREBY THE RELATIVE POSITION OF SAID SLIDER CONTACT ON SAID RESISTANCE ELEMENT MAY BE ADJUSTED INDEPENDENTLY OF ITS MOVEMENT THROUGH ROTATION OF SAID SHAFT. 